Matrix converters may be used in electric and/or hybrid vehicles to accommodate delivery of relatively high power over a relatively wide range of operating voltages, while at the same time achieving galvanic isolation, relatively high power factors, low harmonic distortion, relatively high power density and low cost. For example, bidirectional isolated matrix converters may be used to deliver energy from an alternating current (AC) energy source, such as the single-phase grid electricity common in most residential and commercial buildings, to charge a direct current (DC) energy storage element, such as a rechargeable battery, in a vehicle.
Often, an inductor is present between the AC energy source and the matrix converter. Interrupting the inductor current may result in undesirable and potentially damaging voltage spikes across components of the matrix converter. During a switching cycle, the matrix converter alternates between circulating (or free-wheeling) the inductor current and delivering energy (or current) to the DC energy storage element with a duty cycle that achieves a desired power flow from the AC energy source to the DC energy storage element. However, due to parasitic and leakage inductances within the matrix converter hardware, transitioning from circulating the inductor current to delivering energy may also produce undesirable and potentially damaging voltage spikes across components of the matrix converter.
One common approach to this problem involves the use of snubber circuits configured electrically in parallel across switches of the matrix converter. However, this approach adds lossy components to the system that reduce efficiency and increase costs. Another approach involves the use of soft switching techniques by adding resonant inductors or quasi-resonant snubbers. This approach also add components, reduces efficiency, and increases costs and circuit complexity.